Is urinary neutrophil gelatinase-associated lipocalin able to predict acute kidney injury episodes in very low birth weight infants in clinical settings?

Background: We evaluated the potential utility of elevated urinary neutrophil gelatinase-associated lipocalin (UNGAL) concentration as a screening test for early identification of acute kidney injury (AKI) in very low birth weight (VLBW) newborns. Methods: Urine for UNGAL analysis was collected prospectively daily until 32 wk postmenstrual age in 91 VLBW newborns, yielding 2,899 specimens. UNGAL values > 50 ng/ml were considered elevated. AKI was defined as two or more consecutive elevations in s[Cr] above the 95 th percentile adjusted for gestational age and chronological age within a 48 h period. We compared UNGAL values taken during the 5 d prior to AKI onset (pre-AKI) to values taken during non-AKI days. Results: Overall, 15 episodes of AKI were identified in 13 infants. UNGAL was available in 44 pre-AKI days and 969 non-AKI days. UNGAL > 50 ng/ml occurred more often in pre-AKI days than in non-AKI days (risk ratio 3.48 (1.89, 6.40)). Positive and negative likelihood ratios were 1.92 (1.52, 2.41) and 0.52 (0.34, 0.78), respectively. Conclusion: Although UNGAL elevation > 50 ng/ml discriminates between pre-AKI and non-AKI days, high false positive and false negative rates limit utility as a screening test in VLBW newborns.